The present invention relates to article positioners in general and, more particularly, to an X, Y, Z and .theta. article positioner that utilizes a plurality of sliding wedges to mutually independent movement in one or more orthogonally related directions.
The use of wedges to position an article is known in the art. See: U.S. Pat. No. 1,218,771, "Mechanical Movement", issued Mar. 13, 1917; U.S. Pat. No. 3,266,329, "Mechanical Movement", issued Aug. 16, 1966; and, U.S. Pat. No. 4,213,509, "Hydrostatic Setting Apparatus For Support Of Loads", issued July 22, 1980.
Article positioners per se are used in a variety of industries. For example, in the semiconductor industry X, Y, Z and .theta. "tables" are employed to position a semiconductor wafer with respect to the testing head of a wafer prober. The semiconductor wafer is positioned in X, Y and .theta. and then moved in the Z axis to contact the wafer prober. After testing, the wafer is moved in the opposite direction along the Z axis and then positionally adjusted with respect to a new test point in X, Y and .theta. orientation. In this example, the Z axis movement is significantly less than movement in the X and Y axes. Not only is the Z axis movement smaller, but the positional resolution constraint is significantly tighter. Furthermore, it is important to have the table relatively stiff in the Z axis as opposed to the X and Y axes.
It is accordingly a general object of the present invention to provide an improved X, Y, Z and .theta. article positioner.
It is a specific object of the invention to provide an article positioner that employs a plurality of sliding wedges to achieve mutually independent movement in at least two orthogonally related axes.
It is a further object of the invention to provide an article positioner that is relatively stiff in one axis as compared to the stiffness in the other axes of movement.
It is a feature of the invention that the article positioner provides greater travel in the X direction as compared to a conventional article positioner having a similar "footprint".
It is another feature of the invention that the article positioner provides greater X speed and greater X acceleration when compared to traditional article positioners.
It is still a further feature of the invention that stiffness in the Z direction is significantly increased together with increased resolution in the Z direction.